EP0472778B1 - Linear translation unit - Google Patents

Description

In the present invention, it is a linear unit, in particular a device for processing, transporting and manipulating workpieces, with a housing and a slide which is movable from the housing and is designed as a box profile and is provided with guide rods and on which a handling device or the like. is fixable for the workpiece, whereby in the housing there may be staggered opposite adjustable bearings, between which the slide slides.

Linear units of this type are known, for example, from FR-A-2 530 526 and are used in trade and industry when it comes to performing repetitive work steps. Such linear units can perform linear movements in particular. Units are known which have only two end positions and those which have one or more holding positions.

Basically, such linear units are almost identical in their nature and construction. A carriage is arranged in a housing and has a carrier plate at one end, namely where it emerges from the housing. Appropriate tools, handling devices, rotary units or the like are to be attached to such a carrier plate, which, for example, grip a workpiece to be machined and bring it into the desired working position. A pneumatic device that pushes the slide out of the housing or moves it back into the starting position preferably provides for the linear displacement of the workpiece.

In general, such a carriage consists of one, but preferably two guide rods, to which the carrier plate is assigned on the one hand and which slide in corresponding bearings. The guide rods are often elongated piston rods from the pistons that set the slides in motion.

A disadvantage of such units, however, has often been shown that the slide is no longer absolutely dimensionally stable on longer strokes, in particular when machining heavy workpieces. By twisting or bending the guide rods accordingly, you can accept, albeit minimally, noticeable, undesirable inaccuracies.

A linear unit is known from FR-A 2 530 526, for example, in which box profiles move telescopically into one another. One box profile is based on guide rails on rollers, which are not shown, are stored. No adjustment of the bearing clearance is provided, which turns out to be a considerable disadvantage during the relatively long life of such a linear unit.

On the other hand, adjustability of a bearing play is shown in WO-A 8 707 454. There, a block-like tool carrier moves within a box-shaped housing, roller or ball bearings being used for the longitudinal guidance of the tool carrier. Some of these bearings are supported on the outside on a pressure plate, which can be adjusted by means of a screw to eliminate bearing play. In the area of the bearings, the tool carrier is also covered with strips made of a hard, wear-resistant material.

Another disadvantage of such units is the arrangement of the end stops. Since they are mostly outside the bearing level of the slide, high torsional forces also occur when they are struck, which can lead to inaccurate dimensions or increase material wear.

Another major disadvantage of the linear units of the type described above is that intermediate positions between the end stops can only be set up in certain areas and not over the entire stroke length. However, a simple, infinitely variable adjustment of intermediate stops over the entire stroke length is a constantly required requirement.

All of these are disadvantages that are either time-consuming, material-consuming or costly in use.

The inventor set himself the task of creating a linear unit of the above. To create a way that is very dimensionally stable and works precisely and allows a great versatility in the area of application due to the continuously adjustable intermediate positions.

To achieve this object, the guide rods are of round cross-section and the bearings designed as ball bearings are partially reproduced in accordance with the shape of the guide rod, with at least one of the opposing ball bearings being seated on an axle bolt which, on the one hand, engages with a threaded section in a sleeve-shaped clamping nut and on the other hand is supported by a bolt section against a screw bolt, the axle bolt, threaded section, bolt section and screw bolt being arranged with their axes perpendicular to the guide rod and the axis of the axle bolt being axially parallel to the axis of the adjacent bolt section and the threaded section.

The roller bearing consists of ball bearings, which are arranged in the housing and interact with guide rods that are fixed in or on the box section. The ball bearings are seated on an axle bolt, on which a threaded section is formed on the one hand and a slotted head is preferably formed on the other hand via a bolt section. The threaded section engages in a clamping nut. The clamping nut and bolt section are supported against molded-on strips or webs, which thus form an abutment against the guide rod.

The slotted head molded onto the bolt section abuts a shoulder on a web. At this point, the web is milled exactly flat over its entire length, so that all successive slot heads and thus also the axle bolts and ball bearings assume an exact position.

In addition, another screw bolt penetrates into the slotted head, which serves to support the entire bearing. Here, a correspondingly shaped head of this bolt passes through a housing bore in which it sits snugly and on the other hand fixes or braces the bolt section and thus the entire axle bolt in the housing. By using an approximately eccentric axle bolt, it is conceivable that the ball bushings can also be slightly changed or adjusted radially.

The adjustability of the ball bearings ensures that they run the guide rods assigned to the box profile so that the side walls of the Box profile are absolutely parallel to the inner wall of the housing, ie the box profile or the slide can be set up in the housing. The ball bearings or the axle bolts carrying the ball bearings can, if necessary, be arranged offset in the housing.

A corresponding lubrication device is provided so that the slide or the guide rods can roll smoothly and easily over the ball bearings. A lubricating device according to the invention consists of felt pads or felt pens which are impregnated with an appropriate lubricant. These lubrication plates or lubrication pins are mounted in corresponding holders, these holders being arranged at various points along the guide rods in front of or behind the ball bearings. The arrangement is determined in such a way that, in the position of use, the guide rods slide over these felt pads or felt-tip pens under slight pressure, thus absorbing each of the lubricants. Appropriate lubrication of the guide rods is guaranteed even with high permanent loads and high loads, dry running or sticking of the guide rods is excluded. The felt pads or felt-tip pens are easily soaked with lubricant or can be replaced as a whole.

A cylinder, in particular a cylinder to which pressure can be applied, engages in the box section forming the slide, this cylinder preferably being connected in an articulated manner to a cylinder holder fastened to an end plate.

The cylinder holder has an approximately forked shape, in which a bearing eye of the cylinder engages. To fix it, a bolt passes through the mounting fork and the bearing eye. In addition to this type of mounting, a cardanic mounting is also conceivable. On the other hand, this mounting has a piston rod assigned to the cylinder connected to a driver. The driver is fixed in the interior of the box profile forming the slide and on the box profile itself. The connection between the driver and the piston rod is preferably created by a coupling, which is screwed into a corresponding threaded hole in the driver on the one hand and on the other hand to the piston rod with a corresponding external thread and is fixed by a lock nut. Any play occurring between the driver and the piston rod can thus be compensated for exactly. The driver is also releasably attached to the box profile by appropriate fasteners. This type of attachment allows the slide or the cylinder or both to be replaced easily and quickly if necessary.

Connections to a pressure source are provided on the end plate for actuating the piston rod. When the cylinder is pressurized with pressure medium, the movement of the piston rod is transmitted to the slide so that it moves out of the housing or into the housing. The use of a box profile for the slide and the way the slide is mounted in the housing ensure high stability. The box profile itself is characterized by high dimensional stability.

This arrangement ensures a torsion-resistant load-bearing capacity with high dimensional accuracy even with a relatively long stroke. In order to be able to set different stroke lengths or end positions for the slide, approximately T-shaped longitudinal grooves are formed laterally parallel to one another in the box profile. In these longitudinal grooves, stops can be fixed using T-nuts. The fixing takes place by means of corresponding fastening elements, such as threaded bolts or the like. By loosening these fastening elements, the stops can be moved continuously along these longitudinal grooves. A shock absorber is assigned to these stops for the final determination of an intermediate position or an end position. It is arranged parallel to the longitudinal groove and is supported in a shock absorber holder. The shock absorber holder is fixed in a radial bore in a piston by means of a threaded bolt. The piston runs vertically to the central axis of the shock absorber within a cylindrical bore in a step stop plate. The step stop plate closes the opening of the housing around the slide. Chambers are formed on both sides of the piston within the cylindrical bore. These chambers are each closed by covers, which are clamped by bearing bolts that press on the covers. Sealing rings in the lids or around the pistons ensure that the chambers are airtight. Of course, screw closures or the like are also conceivable for the closure of the chambers, such closures being more expensive and less maintenance-friendly.

Nipple locks are screwed into the chambers on both sides of the piston. These plug nipple closures are each connected to a line carrying the pressure medium, which is led through the housing and connected to connections on the end plate.

The piston is moved by pressurizing the chambers. In accordance with this movement, the position of the shock absorber holder and with it the shock absorber inevitably is changed within a recess provided for this purpose in such a way that it changes the paths of the stops in each case.

For example, if the carriage moves out of the housing, a first stop hits the shock absorber in its path. The carriage is stopped in a first stop position. After a desired time, the shock absorber changes its position level and releases the first stop. The carriage can continue to move out of the housing until the second stop hits the shock absorber, which is now in its plane. The final end position of the lifting movement has been reached.

Compared to the shock absorber described above, the slide has a further stop which interacts with a shock absorber fitted into the end plate in the rear area of the housing. The stop and this shock absorber determine the end position or the starting position for the retracted slide.

Progressively working hydraulic shock absorbers are preferably used to dampen the impact of the stops or to dampen the sled braking in the area of the stop or end position.

The pneumatics, which cause both the stroke movement and the height adjustment or change of position of the shock absorbers, are preferably controlled by inductive proximity switches. Proximity switches are provided in the area of the shock absorbers or in the area of the end positions of the stops, which report the respective end or intermediate position of the slide. The proximity switches are held in plastic sleeves, which can be clipped into corresponding holes in the housing. This type of mounting of proximity switches enables them to be replaced quickly and easily.

Mounting openings are provided on the side of the housing for setting or changing the position of the stops determining the intermediate positions and end positions. To cover the assembly openings in the position of use, guide rails are attached, into which cover plates, preferably in the form of plastic strips, can be inserted. In other exemplary embodiments, such cover plates can also be screwed on or attached by means of special fastening elements.

A dovetail or trapezoidal rail is formed on the underside of the housing. This rail is provided for releasable attachment to a corresponding holder. A unit equipped in this way can be moved or adjusted continuously over its entire length without great effort. Together with the intermediate stops, a linear unit equipped in this way can be optimally set up.

The main idea of the invention of such a linear unit lies above all in the use of a box profile for the formation of the slide. Such a box profile has a very high dimensional stability, which ensures high accuracy. The arrangement of the end and intermediate stops is also particularly noteworthy. The quick and easy way to set intermediate positions continuously simply by moving the stops in the slot tracks makes the linear unit of the type mentioned above universally applicable.

Figur 1

eine teilweise aufgebrochene Seitenansicht einer erfindungsgemässen Lineareinheit;

Figur 2

einen Längsschnitt durch die Lineareinheit gemäss Figur 1 entlang II-II;

Figur 3

einen vergrösserten Querschnitt durch die Lineareinheit entlang Linie III-III in Figur 1;

Figur 4

einen Ausschnitt eines vergrösserten Querschnittes durch die Lineareinheit entlang Linie IV-IV in Figur 1;

Figur 5

eine Draufsicht auf eine Stirnplatte der Lineareinheit.

Further details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

Figure 1

a partially broken side view of a linear unit according to the invention;

Figure 2

a longitudinal section through the linear unit according to Figure 1 along II-II;

Figure 3

an enlarged cross section through the linear unit along line III-III in Figure 1;

Figure 4

a section of an enlarged cross section through the linear unit along line IV-IV in Figure 1;

Figure 5

a plan view of an end plate of the linear unit.

According to FIG. 1, a linear unit R has a housing 1 which, as can be seen above all in FIG. 3, has the shape of a closed, approximately rectangular profile.

While the housing 1 forms a flat top 2, a cross-sectionally dovetail or trapezoidal rail 4 is formed on its bottom 3. Side surfaces 5 and 6 have guide channels 7 for receiving cover plates 8 (see FIG. 5). These cover plates 8 are, for example, plastic strips which are provided for closing or releasing assembly openings 9.

A carriage 11 is inserted into the housing 1 for the transmission of a linear movement. The carriage 11 consists of a box section 12 with an approximately rectangular cross section. According to FIG. 3, it is displaceably arranged on the left-hand side in the interior of the housing 1 so that a free channel 13 is formed in the housing 1 on the right-hand side. The carriage 11 protrudes from the housing 1 on one side and is equipped on the front side on this side with a carrier plate 10 for receiving a further linear unit, a gripper, pliers, a rotating unit or the like. As can be seen particularly in FIG. 2, the carriage 11 is penetrated by a cylinder 16, in which a piston rod 17 can be set in motion by a piston, not shown, to which pressure medium, in particular compressed air, is applied.

The cylinder 16 is supported on the one hand in a cylinder holder 20 which is fixed to an end plate 21. The cylinder holder 20 projects with a receiving fork 22 on the end face into the slide 11, a bearing eye 23 on the cylinder 16 engaging in this receiving fork 22. For final fixing, a bolt 24 passes through the bearing eye 23 in the receiving fork 22.

On the other hand, the piston rod 17 is connected to a driver 30 which is screwed to the slide 11 by at least one, but preferably by two countersunk screws 32. The piston rod 17 engages with a set screw 33 in the driver 30 and is fixed by a lock nut 36.

For the actuation of the piston rod 17, connections 38 to a pressure source are provided on the end plate 21. When pressure is applied to the cylinder 16, the movement of the piston rod 17 is transmitted to the slide 11, so that it moves out of the housing 1 in the direction x. The slide 11 slides between ball bearings 14. These run in or on the box section 12, preferably hardened and ground guide rods 15. These ball bearings 14 sit above and below the slide 11 approximately in the center of the housing 1 on an axle bolt 39 which engages after the ball bearing 14 with a threaded portion 37 in a sleeve-shaped clamping nut 40. At the other end of the threaded section 37, a slotted head 41 is formed on the axle pin 39 after a pin section 34, which slits with a shoulder 25 against a web 26 of the housing 1. The corresponding stop area of the web 26 is milled flat over its entire length, so that the successive ball bearings 14 can be precisely adjusted.

A further screw bolt 27 penetrates into the head 41 as a support, the head 28 of which sits snugly in a housing bore 29.

The axle pin 39 is also formed slightly eccentrically on the pin section 34, so that a play between the ball bearing 14 and the guide rod 15 can be minimized during rotation.

In order to ensure the smooth movement of the slide 11, in particular the sliding of the guide rods 15 on the ball bearings 14, felt pads 42 or felt pens 43 which can be impregnated with an appropriate lubricant are provided in the housing 1. As can be seen in particular in FIG. 4, the felt pads 42 are arranged between the ball bearings 14 with the aid of corresponding pad holders 44 such that the guide rods 15 slide over them under moderate pressure in the position of use and take up lubricant from the felt pads 42 or felt pens 43.

The use of a box profile 12 for the slide 11 on the one hand and the type of mounting of the slide 11 on the other hand ensure a high torsion-resistant load-bearing capacity of the slide 11 even with a relatively long stroke. A correspondingly occurring external stress is absorbed in particular by the ball bearings 14 via the guide rods 15. A high dimensional stability is achieved.

In order to set different stroke lengths or end positions for the slide 11, the linear unit R has corresponding stops 45 and 46. To set it, two box-shaped longitudinal grooves 47 and 48 are formed in the box profile 12 laterally parallel to the channel 13.

With the aid of T-nuts 49 and corresponding fastening elements 50, such as threaded bolts or the like, the stops 45 and 46 can be fixed and loosened and can thus be moved continuously along these longitudinal grooves 47 and 48.

On the one hand, a shock absorber 55 is assigned to the stops 45 and 46 for the final determination of an end position or an intermediate position. The shock absorber 55 is arranged parallel to the longitudinal groove 47 or 48 and is supported in a shock absorber holder 56. The shock absorber holder 56 is fixed in a radial bore 59 in a piston 58 by means of a threaded bolt 57 or the like. The piston 58 extends vertically to the central axis of the shock absorber 55 within a cylindrical bore 60 in a step stop plate 54.

The cylindrical bore 60 is closed on both sides of the piston 58 by covers 61, which are fixed in a clamped manner by bearing bolts 62, these pressing on the covers 61. A chamber 63 or 64, which can be acted upon with a pressure medium, in particular with compressed air, is formed between the pistons 58 and the covers 61. The chambers 63 and 64 are connected to lines 68 and 69 carrying the pressure medium via plug-in nipple screw connections 67. These have connections 65 and 66 on the end plate 21 (see FIG. 3).

By acting on the chamber 63 or 64 with pressure medium, the piston 58 is moved in the y direction. Corresponding to this movement, the shock absorber holder 56 and with it the shock absorber 55 in its position are changed within a recess 70 provided for this purpose in the step stop plate 54 or in the cylindrical bore 60, in such a way that it comes to rest on the one hand in the plane of the T-shaped longitudinal groove 47 or the stop 45 and on the other hand in the plane of the T-shaped longitudinal groove 48 or the stop 46.

By appropriately arranging the stops 45 and 46 along the T-shaped longitudinal groove 47 and 48 on the one hand and by changing the position of the shock absorber 55 on the other hand, desired stroke movements can be achieved or end or intermediate positions of the slide 11 can be set.

Inductive proximity switches 71 ensure that an end or intermediate position of the stops 45 and 46 is recognized. These proximity switches 71 register the respectively arriving stop 45 and 46. The proximity switches 71 are located in plastic carriers 76 and are clipped into holes 77 in the housing 1. They are accessible from the outside and are easy to replace.

An end stop 72, which interacts with a shock absorber 73, is assigned to the carriage 11 toward the end plate 21. An inductive proximity switch 74 of the type mentioned above is also assigned to this end stop 72.

Due to the dovetail or trapezoidal rail 4 described above over the entire length of the underside 3 of the housing 1, this linear unit R can be displaced and clamped over the entire length on a corresponding holding device.

Claims (13)

1. Linear unit, in particular an apparatus for the machining, transportation and manipulation of workpieces, with a housing (1) and a carriage (11) which is movable from the housing (1), is designed as a box profile, is provided with guide rods (15) and on which a handling device or the like for the workpiece may be fixed, wherein adjustable bearings (14) between which the carriage (11) is slidably mounted are arranged opposite one another, optionally in an offset manner, in the housing (1), characterised in that the guide rods (15) are designed so as to be round in cross section and the bearings (14) designed as ball bearings are designed in part to correspond to the shape of the guide rods, wherein at least one of the mutually opposed ball bearings (14) rests on an axle bolt (39) which, on the one hand, engages with a threaded portion (37) in a sleeve-shaped clamping nut (40) and, on the other hand, rests via a bolt portion (34) against a screw bolt (27), axle bolt (39), threaded portion (37), bolt portion (34) and screw bolt (27) being arranged with their axes perpendicularly to the guide rod and the axle of the axle bolt (39) extending with its axis parallel to the axis of the adjacent bolt portion (34) and of the threaded portion (37).
2. Linear unit according to claim 1, characterised in that the bolt portion (34) is connected to a slotted head (41) into which the supporting threaded bolt (27) penetrates.
3. Linear unit according to claim 2, characterised in that the slotted head (41) strikes a web (26) of the housing (1).
4. Linear unit according to one of claims 1 to 3, characterised in that the guide rods (15) are allocated lubricating arrangements (42, 43).
5. Linear unit according to at least one of claims 1 to 4, characterised in that at least one groove (47, 48) for fixing at least one stop (45, 46, 72) is shaped into the carriage (11).
6. Linear unit according to claim 5, characterised in that the stop (45, 46, 72) is allocated a shock absorber (55, 73) as an end stop at least on one side.
7. Linear unit according to claim 6, characterised in that the shock absorber (55) may be removed from the path of the stop (45, 46, 72).
8. Linear unit according to claim 7, characterised in that, perpendicularly to the path of the stop (45, 46, 72), a piston (58) slides in a cylindrical bore (60), the piston (58) holding or guiding the shock absorber (55) in a recess (70).
9. Linear unit according to claim 8, characterised in that a chamber (63, 64) is formed on both sides of the piston (58) in the cylindrical bore (60) and may be loaded by a pressure medium.
10. Linear unit according to claim 9, characterised in that the chambers (63, 64) are closed by covers (61) on the other side of the piston (58), closure taking place by means of the clamping nuts (40) which press on the covers (61) so that the covers (61) are fixed in a clamping manner.
11. Linear unit according to one of claims 5 to 10, characterised in that the stop (45, 46, 72) is allocated at least one proximity switch (71, 74) for detecting an end position, the proximity switch (71, 74) being mounted in a plastic carrier (76) which can be snapped into a housing hole (77).
12. Linear unit according to at least one of claims 1 to 11, characterised in that the housing (1) has assembly orifices (9) which are covered in the position of use by cover plates (8).
13. Linear unit according to at least one of claims 1 to 12, characterised in that the housing (1) has a dovetail-shaped or trapezoidal rail (4) for releasable fixing to a mounting.

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